Liquid crystals (LCs) are extensively used for applications that include display and sensing technologies. Design of new lyotropic liquid crystals (liquid crystalline phases that form in the presence of solvent) has been limited relative to the design of LCs that form without solvent. Lyotropic liquid crystals have been recently used in directing polymerization reactions, protein structure determination, templating inorganic materials, aligning carbon nanotubes and bio-sensing. Because of this functional diversity, identification of new molecules capable of forming lyotropic LC phases (mesogens) remains an important goal.
Lyotropic liquid crystalline phases that form in water have been created with surfactants, aromatic dyes, synthetic polymers and biopolymer assemblies such as DNA, viruses, polysaccharides, collagen, and other polypeptides. Systematic evaluation of factors that modulate LC behavior is often difficult in these systems because rational and incremental modification of mesogen structure is not readily achieved.
It is well-known that α-helical poly(α-amino acids) are capable of forming lyotropic liquid crystalline phases. Poly-α-peptides must be quite long, however, to form LC phases. In general, this length requirement has necessitated the use of materials that are polydisperse in size and limited in sequence, which has hampered exploration of sequence-property correlations. Short oligomers of beta-amino acids (beta-peptides) are attractive for systematic study of assembly processes because beta-peptides can display a diverse range of functionalized side chains, and these oligomers fold into compact and stable conformations that orient the side chains in predictable ways. Beta-peptides have been shown to self-assemble in dilute solution and on gold surfaces, as well as to associate with microbial membranes.
Accordingly, it is desirable to design and synthesize modular scaffolds based on beta-peptides for use in LC phase behavior studies and, ultimately, industrial applications.